ISO 286 Limts & Fits 1

[Eyke]

I have a design guide for wear rings which uses the ISO standard limits & fits for the bore dia and groove diameter. I don't have this spec and wonder what would be the tolerances on a couple of dimentions.

First one is the bore diameter. It would be 16.501 H9. (In actuality the T-Seal would govern this dimension) The groove diameter would be 16.501 dia - .250 h8. This is the more important tolerance.

Could someone tell me what the tolerance would be for these two dimensions? Or, if possible, a web site that lists these limits and fits.

Thank you.
Eyke

 

[gearguru]

My favorite topic!!!
16.501 H9 = 16.501 +0.043/-0.0
16.501 h8 = 16.501 +0.0/-0.027
I do not understand "16.501 dia - .250 h8".
ISO fits charts are in any ball bearing company catalog - at least good selection of fits used in bearings;
Also in Machinery's Handbook. Try to understand how they work, it is an excellent design tool. We had in this forum discussion about it before.
gearguru

 

[gearguru]

I looked again on your posting. The groove in the 16.501 shaft is 0.25mm deep? Or it is 0.125 deep for total dia being 0.25 smaller?
1. If it is 0.25 deep, then your nominal dia will be
16.501-2*0.25 h8 = 16.001 h8 = 16.001 +0/-0.027
2. If it is 0.125 deep then 16.501 - 0.25 = 16.251
And 16.251 h8 = 16.251 +0/-0.027

Note: the tolerances for dimensions over 10.0 to 18.0 included, are the same. ISO tolerances are always assigned to a "groop" of sizes.

Look on Thread404-14730 in this forum.
gearguru

 

[Eyke]

Thanks Gearguru.

I did look in the Machinery's Handbook (25th Ed), but did not see h8 for the shaft tolerance, unless I'm not reading this right. I did have a look at the thread you mentioned. I'll have to read it again to fully grasp what you were saying.

AFA the 16.501 dia - .250 h8, the groove dia is .250" less than the bore dia. The slot would be .250 less 1/2 the diametrical clearance deep. This is for piston wear rings.

Are your numbers in metric or English? .043 seems like a lot of tolerance for a wear ring. I ran the conversion and it comes to .0017, which sounds a little closer to what I'd expect.

The tolerance of the bore dia for the t-seal is +.004/-.000.

Thanks for the info, now if I can find that Timkin bearing catalog....

Cheers!
Eyke

 

[Eyke]

Hmmm.....lets look at the last page of the wear ring book...oh...yeah...there it is, tolerances for h8 & h9, H8 & H9, in mm.

Guess that should answer the question.

Thanks for you help.

 

[gearguru]

My pleasure
When working with ISO fits, be sure that your dimensions are in mm.
gearguru

 

[Prboz]

I'm looking for a table of iso tolerences on the net has anybody got a good url?

Prboz

 

[gearguru]

Prboz,
Try to search using Google, Yahoo etc.
There are some pages with selected ISO fit charts on the Net.
I lately found this page:

http://www.tecnologix.com/en/tools/fset_.html

You can find there a nice calculator for the fit, actual min/max dimensions (if you know the nominal and tolerance symbol) and clearance/interference.
gearguru